Symmetrical lateral bipolar junction transistor and use of same in characterizing and protecting transistors

ABSTRACT

A symmetrical lateral bipolar junction transistor (SLBJT) is provided. The SLBJT includes a p-type semiconductor substrate, a n-type well, an emitter of a SLBJT situated in the n-type well, a base of the SLBJT situated in the n-type well and spaced from the emitter by a distance on one side of the base, a collector of the SLBJT situated in the n-type well and spaced from the base by the distance on an opposite side of the base, and an electrical connection to the substrate outside the n-type well. The SLBJT is used to characterize a transistor in a circuit by electrically coupling the SLBJT to a gate of the test transistor, applying a voltage to the gate, and characterizing aspect(s) of the test transistor under the applied voltage. The SLBJT protects the gate against damage to the gate dielectric.

BACKGROUND OF THE INVENTION

Technical Field

The present invention generally relates to characterizing and protectingtransistors. More particularly, the present invention relates tosymmetrical lateral bipolar junction transistors and the use thereof incharacterizing and protecting transistors.

Background Information

During the manufacture of integrated circuits withmetal-oxide-semiconductor field-effect transistors, one common problemis gate oxide damage caused by the “antenna effect,” more formally knownas plasma-induced gate oxide damage. This type of damage can potentiallycause yield and reliability problems for such integrated circuits.Currently, diodes are used to protect such transistors duringcharacterization thereof. However, the use of diodes sufferslimitations, such as the inability to measure gate-induced drain leakagecurrent or gate leakage current, and inaccuracies in other testingcharacteristics.

Therefore, a need exists for improved characterization and protection oftransistors.

SUMMARY OF THE INVENTION

The shortcomings of the prior art are overcome and additional advantagesare provided through the provision, in one aspect, of a method ofcharacterizing a transistor. The method includes providing a testtransistor, the test transistor including a gate and a gate dielectricmaterial. The method further includes providing a symmetrical lateralbipolar junction transistor (SLBJT), electrically coupling the SLBJT tothe gate of the test transistor, applying a voltage to the gate,including applying one of a positive voltage and a negative voltage tothe gate, and characterizing one or more aspects of the test transistorunder the applied voltage. The SLBJT protects the gate against damage tothe gate dielectric material, the characterizing includes measuring acurrent at one or more of the gate, the source, the drain and thesubstrate.

In accordance with another aspect, a symmetrical lateral bipolarjunction transistor (SLBJT) is provided. The SLBJT includes a p-typesemiconductor substrate, at least one well, and a first implant regionof a first type for an emitter of a symmetrical lateral bipolar junctiontransistor (SLBJT). The first implant region is situated in one of theat least one well and the first type is one of n-type and p-type.Further, the SLBJT includes a second implant region of a second typeopposite the first type for a base of the SLBJT, the second implantregion being situated in the at least one well and spaced from theemitter on a first side of the base by a distance. Further, the SLBJTincludes a third implant region of the first type for a collector of theSLBJT, the third implant region being situated in the at least one welland spaced from the base on a second side of the base opposite the firstside by the distance. Further, the SLBJT includes a p-type implantregion for electrically coupling to the substrate, the p-type implantregion being situated outside the at least one well.

In accordance with yet another aspect, a circuit is provided. Thecircuit includes a test transistor including a gate, and a symmetricallateral bipolar junction transistor (SLBJT). The SLBJT includes anemitter, a base and a collector. A distance between the emitter and thebase is a same distance as that between the base and the collector, theemitter and the collector being on opposite sides of the base, and theemitter is electrically coupled to the gate of the test transistor.

These, and other objects, features and advantages of this invention willbecome apparent from the following detailed description of the variousaspects of the invention taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts one example of a circuit for characterizing one or moreaspects of a test transistor, the test transistor including asemiconductor substrate, a gate, a source and a drain, the circuitincluding a symmetrical lateral bipolar junction transistor, referred toherein as a “SLBJT” (PNP type in this example) electrically coupled toand for the protection of the test transistor against damage to a gatedielectric material in the test transistor from high voltage, inaccordance with one or more aspects of the present invention.

FIG. 2 is similar to FIG. 1, except that one example of a PNP SLBJT isused, instead of the PNP SLBJT of FIG. 1, in accordance with one or moreaspects of the present invention.

FIG. 3 is a cross-sectional view of one example of a planar PNP SLBJT,including a p-type substrate, a n-type well situated in the substratebetween regions of isolation material, a p-type implant for the emittercontact, a n-type implant for the base contact and a second p-typeimplant for the collector contact, a same distance and isolationmaterial separating the emitter from the base and the base from thecollector on an opposite side of the base than the emitter, the planarPNP SLBJT also including a p-type implant outside the n-type well forelectrically coupling to the substrate contact 158, in accordance withone or more aspects of the present invention.

FIG. 4 is a cross-sectional view of one example of a planar NPN SLBJT,including a p-type substrate, a p-type well in the substrate betweenregions of isolation material, a n-type well, a “triple” n-type well, an-type implant for the emitter contact, a p-type implant for the basecontact and a second n-type implant for the collector contact, a samedistance and isolation material separating the emitter implant from thebase implant and the base implant from the collector implant on theopposite side of the base implant from the emitter implant, the planarNPN SLBJT also including a p-type implant outside the n-type well forelectrically coupling to the substrate via a substrate contact, inaccordance with one or more aspects of the present invention.

FIG. 5 is a cross-sectional view of one example of a non-planar PNPSLBJT, including a p-type substrate (or p-type well in a substrate ofn-type), a raised structure coupled to the substrate, the SLBJT alsoincluding a n-type well in the raised structure between regions ofisolation material, a p-type implant for the emitter with p-typeepitaxial material thereon, a n-type implant for the base with n-typeepitaxial material hereon, and a p-type implant for the collector withthe p-type epitaxial material thereon, a same distance and isolationmaterial separating the emitter from the base on one side, and the basefrom the collector on the opposite side, the non-planar PNP SLBJT alsoincluding a p-type implant separate from the n-type well with the p-typeepitaxial material thereon for electrically coupling to the substrate,in accordance with one or more aspects of the present invention.

FIG. 6 is a cross-sectional view of one example of a non-planar NPNSLBJT, including a p-type substrate (or p-type well in a substrate ofn-type), a raised structure coupled to the substrate, the SLBJT alsoincluding a n-type well in the raised structure between regions ofisolation material, a p-type well, a “triple” n-type well, a n-typeimplant with n-type epitaxial material thereon for the emitter, a p-typeimplant with p-type epitaxial material thereon for the base, and an-type implant with the n-type epitaxial material thereon for thecollector, a same distance and isolation material separating the emitterfrom the base on one side and the base from the collector on the otherside, the non-planar NPN SLBJT also including a p-type implant separatefrom the n-type well with the p-type epitaxial material thereon forelectrically coupling to the substrate, in accordance with one or moreaspects of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Aspects of the present invention and certain features, advantages, anddetails thereof, are explained more fully below with reference to thenon-limiting examples illustrated in the accompanying drawings.Descriptions of well-known materials, fabrication tools, processingtechniques, etc., are omitted so as not to unnecessarily obscure theinvention in detail. It should be understood, however, that the detaileddescription and the specific examples, while indicating aspects of theinvention, are given by way of illustration only, and are not by way oflimitation. Various substitutions, modifications, additions, and/orarrangements, within the spirit and/or scope of the underlying inventiveconcepts will be apparent to those skilled in the art from thisdisclosure.

Approximating language, as used herein throughout the specification andclaims, may be applied to modify any quantitative representation thatcould permissibly vary without resulting in a change in the basicfunction to which it is related. Accordingly, a value modified by a termor terms, such as “about,” is not limited to the precise valuespecified. In some instances, the approximating language may correspondto the precision of an instrument for measuring the value.

The terminology used herein is for the purpose of describing particularexamples only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprise” (andany form of comprise, such as “comprises” and “comprising”), “have” (andany form of have, such as “has” and “having”), “include (and any form ofinclude, such as “includes” and “including”), and “contain” (and anyform of contain, such as “contains” and “containing”) are open-endedlinking verbs. As a result, a method or device that “comprises,” “has,”“includes” or “contains” one or more steps or elements possesses thoseone or more steps or elements, but is not limited to possessing onlythose one or more steps or elements. Likewise, a step of a method or anelement of a device that “comprises,” “has,” “includes” or “contains”one or more features possesses those one or more features, but is notlimited to possessing only those one or more features. Furthermore, adevice or structure that is configured in a certain way is configured inat least that way, but may also be configured in ways that are notlisted.

As used herein, the term “connected,” when used to refer to two physicalelements, means a direct connection between the two physical elements.The term “coupled,” however, can mean a direct connection or aconnection through one or more intermediary elements.

As used herein, the terms “may” and “may be” indicate a possibility ofan occurrence within a set of circumstances; a possession of a specifiedproperty, characteristic or function; and/or qualify another verb byexpressing one or more of an ability, capability, or possibilityassociated with the qualified verb. Accordingly, usage of “may” and “maybe” indicates that a modified term is apparently appropriate, capable,or suitable for an indicated capacity, function, or usage, while takinginto account that in some circumstances the modified term may sometimesnot be appropriate, capable or suitable. For example, in somecircumstances, an event or capacity can be expected, while in othercircumstances the event or capacity cannot occur—this distinction iscaptured by the terms “may” and “may be.”

Reference is made below to the drawings, which are not drawn to scalefor ease of understanding, wherein the same reference numbers are usedthroughout different figures to designate the same or similarcomponents.

FIG. 1 depicts one example of a circuit 100 for characterizing one ormore aspects of a test transistor 102, the test transistor including asemiconductor substrate 104, a gate 106, a source 108 and a drain 110,the circuit including a symmetrical lateral bipolar junction transistor103, referred to herein as a “SLBJT” (PNP type in this example)electrically coupled to and for the protection of the test transistoragainst damage to a gate dielectric material in the test transistor fromhigh voltage, in accordance with one or more aspects of the presentinvention.

A variable voltage source 105 is electrically coupled to the gate 106 ofthe test transistor 102. The aspects of the test transistor to becharacterized may include, for example, current measurements at the gateand/or the source 108 and/or the drain 110. In addition, the aspects forcharacterization may further include, for example, measuring the currentat substrate 104. The circuit further includes voltage sources 112, 114and 116 for the source, substrate and drain, respectively. All of thevoltage sources, including the variable voltage source, as well ascollector 118 of SLBJT 103 are electrically coupled, directly orindirectly, to a ground 120 of the circuit.

The circuit 100 may be conventionally fabricated, for example, usingknown processes, techniques and measurement equipment. Further, althoughonly a portion is shown for simplicity, it will be understood that, inpractice, many such test transistors and corresponding SLBJT's may beincluded on the same bulk substrate.

In one example, substrate 104 may include any silicon-containingsubstrate including, but not limited to, silicon (Si), single crystalsilicon, polycrystalline Si, amorphous Si, silicon-on-nothing (SON),silicon-on-insulator (SOI) or silicon-on-replacement insulator (SRI) orsilicon germanium substrates and the like. Substrate 104 may in additionor instead include various isolations, dopings and/or device features.The substrate may include other suitable elementary semiconductors, suchas, for example, germanium (Ge) in crystal, a compound semiconductor,such as silicon carbide (SiC), gallium arsenide (GaAs), galliumphosphide (GaP), indium phosphide (InP), indium arsenide (InAs), and/orindium antimonide (InSb) or combinations thereof; an alloy semiconductorincluding GaAsP, AlInAs, GaInAs, GaInP, or GaInAsP or combinationsthereof.

FIG. 2 is similar to FIG. 1, except that a PNP SLBJT 124 is used,instead of the PNP SLBJT of FIG. 1, in accordance with one or moreaspects of the present invention. The results obtained fromcharacterizing test transistor aspects are the same for either the PNPSLBJT 103 or the PNP SLBJT. In other words, for purposes ofcharacterizing the test transistor aspects, the two types of SLBJT's areinterchangeable. The reasoning as to why they produce the same resultswill be discussed below with reference to FIGS. 3 and 4.

FIG. 3 is a cross-sectional view of one example of a planar PNP SLBJT130, including a p-type substrate 132, a n-type well 134 situated in thesubstrate between regions 136 and 138 of isolation material, a p-typeimplant 140 for the emitter contact 142, a n-type implant 144 for thebase contact 146 and a second p-type implant 148 for the collectorcontact 150, a same distance 152 and isolation material 154 separatingthe emitter from the base and the base from the collector on an oppositeside of the base than the emitter, the planar PNP SLBJT also including ap-type implant 156 outside the n-type well for electrically coupling tothe substrate contact 158, in accordance with one or more aspects of thepresent invention.

PNP SLBJT 130 may be conventionally fabricated, for example, using knownprocesses and techniques (e.g., growing epitaxial material andimplanting impurities). In one example, the p-type implant material forthe emitter, collector and substrate are all a same p-type implantmaterial, for example, epitaxial silicon germanium, and/or the n-typeimplant material for the base may be, for example, phosphorus orarsenic. The n-type well may include, for example, phosphorus or arsenicdoped silicon material. The isolation material 136, 154 and 138 mayinclude a same isolation material, for example, a gap fill oxide ornitride, or a combination of both, in shallow (154) and deep (136, 138)trenches. The distance separating the emitter from the base, and thebase from the collector may be, for example, about 0.2 microns to about5 microns, and the implants may each have a depth of about 0.1 micronsto about 0.3 microns.

FIG. 4 is a cross-sectional view of one example of a planar NPN SLBJT160, including a p-type substrate 162, a p-type well 165 in thesubstrate between regions 166 and 168 of isolation material, a n-typewell 164, a “triple” n-type well 167, a n-type implant 170 for theemitter contact 172, a p-type implant 174 for the base contact 176 and asecond n-type implant 178 for the collector contact 180, a same distance182 and isolation material separating the emitter implant from the baseimplant and the base implant from the collector implant on the oppositeside of the base implant from the emitter implant, the planar NPN SLBJTalso including a p-type implant 186 outside the n-type well forelectrically coupling to the substrate via a substrate contact 188, inaccordance with one or more aspects of the present invention.

NPN SLBJT 160 may be conventionally fabricated, for example, using knownprocesses and techniques (e.g., implanting and growing epitaxialmaterial). In one example, the p-type implant material for the base andsubstrate are a same p-type implant material, for example, epitaxialsilicon germanium, and/or the n-type implant material for the emitterand collector may be, for example, phosphorus or arsenic. The n-typewell may include, for example, phosphorus or arsenic doped siliconmaterial, and may include, for example, a “triple” n-well, which isphosphorus or arsenic doped silicon material. The p-type well mayinclude, for example, boron doped silicon material. The isolationmaterial 166, 168 and 184 may include a same isolation material, forexample, a gap fill oxide or nitride, or a combination of both, inshallow (154) and deep (136, 138) trenches. The distance separating theemitter from the base, and the base from the collector may be, forexample, about 0.2 microns to about 5 microns, and the implants may eachhave a depth of about 0.1 microns to about 0.3 microns.

The PNP SLBJT of FIG. 3 and the NPN SLBJT of FIG. 4 are interchangeablefor use in characterizing and protecting a test transistor, becauseoperation of each one in either forward or reverse bias mirrors theopposite bias.

FIG. 5 is a cross-sectional view of one example of a non-planar PNPSLBJT 190, including a p-type substrate 192 (or p-type well in asubstrate of n-type), a raised structure 194 coupled to the substrate,the SLBJT also including a n-type well 196 in the raised structurebetween regions 198 and 200 of isolation material, a p-type implant 202for the emitter with p-type epitaxial material 204 thereon, a n-typeimplant 206 for the base with n-type epitaxial material 208 thereon, anda p-type implant 210 for the collector with the p-type epitaxialmaterial 212 thereon, a same distance 214 and 216 and isolation material218 separating the emitter from the base on one side, and the base fromthe collector on the opposite side, the non-planar PNP SLBJT alsoincluding a p-type implant 220 separate from the n-type well with thep-type epitaxial material 222 thereon for electrically coupling to thesubstrate, in accordance with one or more aspects of the presentinvention.

Non-planar PNP SLBJT 190 may be conventionally fabricated, for example,using known processes and techniques (e.g., implants and epitaxialgrowth). In one example, substrate 190 may include anysilicon-containing substrate including, but not limited to, silicon(Si), single crystal silicon, polycrystalline Si, amorphous Si,silicon-on-nothing (SON), silicon-on-insulator (SOI) orsilicon-on-replacement insulator (SRI) or silicon germanium substratesand the like. Substrate 190 may in addition or instead include variousisolations, dopings and/or device features. The substrate may includeother suitable elementary semiconductors, such as, for example,germanium (Ge) in crystal, a compound semiconductor, such as siliconcarbide (SiC), gallium arsenide (GaAs), gallium phosphide (GaP), indiumphosphide (InP), indium arsenide (InAs), and/or indium antimonide (InSb)or combinations thereof; an alloy semiconductor including GaAsP, AlInAs,GaInAs, GaInP, or GaInAsP or combinations thereof.

In one example, the raised structure(s) may take the form of a “fin.”The raised structure(s) may be etched from a bulk substrate, and mayinclude, for example, any of the materials listed above with respect tothe substrate. Further, some or all of the raised structure(s) mayinclude added impurities (e.g., by doping), making them n-type orp-type.

In one example, the p-type implant material in non-planar PNP SLBJT 190and p-type epitaxial material for the emitter, collector and substratemay all be a same type of material, for example, silicon germanium andepitaxial silicon germanium, and/or the material for the n-type implantand n-type epitaxial material for the base may be, for example,carbon-doped silicon and epitaxial carbon-doped silicon. The n-type wellmay include, for example, phosphorus or arsenic doped silicon material.The isolation material 198, 200 and 218 may include a same isolationmaterial, for example, a gap fill oxide or nitride, or a combination ofboth, in deep trenches. The distance separating the emitter from thebase, and the base from the collector may be, for example, about 0.2microns to about 5 microns, and the implants may each have a depth ofabout 0.1 microns to about 0.3 microns. Finally, a dielectric material224 above the implants may be, for example, a gap fill oxide or nitride,or a combination of both, in shallow trenches.

FIG. 6 is a cross-sectional view of one example of a non-planar NPNSLBJT 230, including a p-type substrate 232 (or p-type well in asubstrate of n-type), a raised structure 234 coupled to the substrate,the SLBJT also including a n-type well 236, a p-type well 235 in theraised structure between regions 238 and 240 of isolation material, a“triple” n-type well 237, a n-type implant 242 with n-type epitaxialmaterial 244 thereon for the emitter, a p-type implant 246 with p-typeepitaxial material 248 thereon for the base, and a n-type implant 250with the n-type epitaxial material 252 thereon for the collector, a samedistance 254 and 256 and isolation material 258 separating the emitterfrom the base on one side and the base from the collector on the otherside, the non-planar NPN SLBJT also including a p-type implant 260separate from the n-type well with the p-type epitaxial material 262thereon for electrical coupling to the substrate, in accordance with oneor more aspects of the present invention.

Non-planar NPN SLBJT 230 may be conventionally fabricated, for example,using known processes and techniques (e.g., implants and epitaxialgrowth). In one example, substrate 230 may include anysilicon-containing substrate including, but not limited to, silicon(Si), single crystal silicon, polycrystalline Si, amorphous Si,silicon-on-nothing (SON), silicon-on-insulator (SOI) orsilicon-on-replacement insulator (SRI) or silicon germanium substratesand the like. Substrate 230 may in addition or instead include variousisolations, dopings and/or device features. The substrate may includeother suitable elementary semiconductors, such as, for example,germanium (Ge) in crystal, a compound semiconductor, such as siliconcarbide (SiC), gallium arsenide (GaAs), gallium phosphide (GaP), indiumphosphide (InP), indium arsenide (InAs), and/or indium antimonide (InSb)or combinations thereof; an alloy semiconductor including GaAsP, AlInAs,GaInAs, GaInP, or GaInAsP or combinations thereof.

In one example, the raised structure(s) may take the form of a “fin.”The raised structure(s) may be etched from a bulk substrate, and mayinclude, for example, any of the materials listed above with respect tothe substrate. Further, some or all of the raised structure(s) mayinclude added impurities (e.g., by doping), making them n-type orp-type.

In one example, the n-type implant material in non-planar NPN SLBJT 230and n-type epitaxial material for the emitter and collector may be asame type of material, for example, carbon-doped silicon and epitaxialcarbon-doped silicon, and/or the material for the p-type implant andp-type epitaxial material for the base and substrate may be, forexample, silicon germanium and epitaxial silicon germanium. The n-typewell may include, for example, phosphorus or arsenic doped siliconmaterial, and may be a “triple” n-well, which may also include, forexample, phosphorus or arsenic doped silicon material. The p-type wellmay include, for example, boron doped silicon material. The isolationmaterial 238, 240 and 258 may include a same isolation material, forexample, a gap fill oxide or nitride, or a combination of both, in deeptrenches. The distance 254 separating the emitter from the base on oneside of the base, and the distance 256 separating the collector from thebase on the other side of the base may be, for example, about 0.2microns to about 5 microns, and the implants may each have a depth ofabout 0.1 microns to about 0.3 microns. Finally, the dielectric material264 above the implants may be, for example, a gap fill oxide or nitride,or a combination of both, in shallow trenches.

In a first aspect, disclosed above is a method of characterizing atransistor. The method includes providing a test transistor, the testtransistor including a gate and gate dielectric material, and providinga symmetrical lateral bipolar junction transistor (SLBJT). The methodfurther includes electrically coupling the SLBJT to the gate of the testtransistor, applying a voltage to the gate, and characterizing aspect(s)of the test transistor under the applied voltage. The SLBJT protects thegate against damage to the gate dielectric material.

In one example, providing the test transistor in the method of the firstaspect may include, for example, providing a planar test transistor, andproviding the SLBJT may include, for example, providing a planar SLBJT.

In one example, providing the test transistor in the method of the firstaspect may include, for example, providing a non-planar test transistor,and providing the SLBJT may include, for example, providing a non-planarSLBJT.

In one example, providing the SLBJT in the method of the first aspectmay include, for example, providing a PNP SLBJT, or as another example,the SLBJT may include a NPN SLBJT.

In one example, applying a voltage in the method of the first aspect mayinclude, for example, applying one of a positive voltage and a negativevoltage to the gate. In another example, the test transistor furtherincludes a source, a drain and a semiconductor substrate, and thecharacterizing includes measuring a current at the gate and/or thesource and/or the drain and/or the substrate.

In one example, the SLBJT includes an emitter, a collector and a base,and providing the SLBJT in the method of the first aspect may include,for example, distancing the emitter from the base on a first side of thebase by a distance, and distancing the collector from the base on asecond side of the base opposite the first side by the same distance.

In a second aspect, disclosed above is symmetrical lateral bipolarjunction transistor (SLBJT). The SLBJT includes a p-type semiconductorsubstrate, well(s), and a first implant region of a first type for anemitter of a symmetrical lateral bipolar junction transistor (SLBJT).The first implant region is situated in one of the well(s) and the firsttype is one of n-type and p-type. Further, the SLBJT includes a secondimplant region of a second type opposite the first type for a base ofthe SLBJT, the second implant region being situated in the well(s) andspaced from the emitter on a first side of the base by a distance.Further, the SLBJT includes a third implant region of the first type fora collector of the SLBJT, the third implant region being situated in thewell(s) and spaced from the base on a second side of the base oppositethe first side by the distance. Further, the SLBJT includes a p-typeimplant region for electrically coupling to the substrate, the p-typeimplant region being situated outside the well(s).

In one example, the SLBJT of the second aspect may further include, forexample, a p-type raised semiconductor structure coupled to thesubstrate, the well(s), the SLBJT, and the substrate implant regionbeing situated in the raised structure. Where the raised structure ispresent, the well(s) may include, for example, a n-type well, theemitter, the collector and a contact for the substrate each includingp-type epitaxial material over the respective implant regions, the baseincluding n-type epitaxial material over the second implant region, andthe implant regions for the emitter, base and collector being situatedin the n-type well. Alternatively, where the raised structure ispresent, the well(s) may include, for example, a p-type well within an-type well and a triple n-type well below the p-type well and n typewell, the emitter and the collector each including n-type epitaxialmaterial over the respective implant regions, the base and a contact forthe substrate each including p-type epitaxial material over therespective implant regions, and the implant regions for the emitter,base and collector being situated in the p-type well.

In one example, the well(s) of the SLBJT of the second aspect mayinclude, for example, a n-type well, and the n-type well and implantregion for the substrate may be, for example, situated in the substrate.Further, the first implant region, the third implant region and thesubstrate implant region may each include, for example, a p-type implantand the second implant region may include, for example, a n-typeimplant.

In one example, the well(s) and the implant region for the substrate ofthe SLBJT of the second aspect may be, for example, situated in thesubstrate, the well(s) including a p-type well within a n-type well anda triple n-type well below the p-type well and n-type well, the firstimplant region and the third implant region each including a n-typeimplant, and the second implant region and substrate implant region eachincluding a p-type implant.

In one example, the distance separating the emitter from the base andthe base from the collector of the SLBJT of the second aspect may be,for example, about 0.2 microns to about 5 microns.

In one example, each of the implant regions of the SLBJT of the secondaspect may have a depth of about 0.1 microns to about 3 microns.

In one example, the SLBJT of the second aspect may have, for example, abreakdown voltage of one of about 9 volts and about 12 volts.

In a third aspect, disclosed above is a circuit. The circuit includes atest transistor having a gate, and a symmetrical lateral bipolarjunction transistor (SLBJT). The SLBJT includes an emitter, a base and acollector. A distance between the emitter and the base on one side ofthe base is a same distance as that between the base and the collectoron an opposite side of the base, and the emitter is electrically coupledto the gate of the test transistor.

In one example, the SLBJT of the circuit of the third aspect mayinclude, for example, one of a planar SLBJT and a non-planar SLBJT.

In one example, the SLBJT of the circuit of the third aspect may be, forexample, one of PNP-type and NPN-type.

In one example, the distance separating the emitter from the base andthe base from the collector of the SLBJT in the circuit of the thirdaspect may be, for example, about 0.2 microns to about 5 microns.

In one example, the SLBJT of the circuit of the third aspect may have,for example, a breakdown voltage of one of about 9 volts and about 12volts, based on a type of gate dielectric used for the test transistor.

While several aspects of the present invention have been described anddepicted herein, alternative aspects may be effected by those skilled inthe art to accomplish the same objectives. Accordingly, it is intendedby the appended claims to cover all such alternative aspects as fallwithin the true spirit and scope of the invention.

The invention claimed is:
 1. A method, comprising: providing a testtransistor, the test transistor comprising a gate and gate dielectricmaterial; providing a symmetrical lateral bipolar junction transistor(SLBJT); electrically coupling the SLBJT to the gate of the testtransistor; applying a voltage to the gate, comprising applying one of apositive voltage and a negative voltage to the gate; and characterizingone or more aspects of the test transistor under the applied voltage,wherein the SLBJT protects the gate against damage to the gatedielectric material, the characterizing comprising measuring a currentat one or more of the gate, the source, the drain and the substrate. 2.The method of claim 1, wherein providing the test transistor comprisesproviding a planar test transistor, and wherein providing the SLBJTcomprises providing a planar SLBJT.
 3. A method, comprising: providing atest transistor, the test transistor comprising a gate and gatedielectric material; providing a symmetrical lateral bipolar junctiontransistor (SLBJT); electrically coupling the SLBJT to the gate of thetest transistor; applying a voltage to the gate, comprising applying oneof a positive voltage and a negative voltage to the gate; characterizingone or more aspects of the test transistor under the applied voltage,wherein the SLBJT protects the gate against damage to the gatedielectric material, the characterizing comprising measuring a currentat one or more of the gate, the source, the drain and the substrate; andwherein providing the test transistor comprises providing a non-planartest transistor, and wherein providing the SLBJT comprises providing anon-planar SLBJT.
 4. The method of claim 1, wherein the SLBJT comprisesone of a PNP SLBJT and a NPN SLBJT.
 5. A method, comprising: providing atest transistor, the test transistor comprising a gate and gatedielectric material: providing a symmetrical lateral bipolar junctiontransistor (SLBJT); electrically coupling the SLBJT to the gate of thetest transistor; applying a voltage to the gate, comprising applying oneof a positive voltage and a negative voltage to the gate; characterizingone or more aspects of the test transistor under the applied voltage,wherein the SLBJT protects the gate against damage to the gatedielectric material, the characterizing comprising measuring a currentat one or more of the gate, the source, the drain and the substrate; andwherein the SLBJT comprises an emitter, a collector and a base, andwherein providing the SLBJT comprises distancing the emitter from thebase on a first side of the base by a distance and distancing thecollector from the base on a second side of the base opposite the firstside by the distance.